Motor drive system

ABSTRACT

A low-frequency torque controller 9 outputs a low-frequency torque controller output τdc* based on a torque command value τ* and a torque detection value τdet, and a vibrational torque controller 11 outputs a vibrational torque command value τpd* based on the torque command value τ*, the torque detection value τdet, and a rotational phase detection value θ. Meanwhile, in a high-frequency resonance suppression controller, an inverter torque command value τinv* is outputted based on the torque detection value τdet and a corrected torque command value τr* obtained by adding the low-frequency torque controller output τdc* to the vibrational torque command value τpd*. The invention thus provides shaft torque vibrational control of a motor drive system wherein engine vibrational torque command values including distortion components are tracked while entirely removing the influence of resonance, non-periodic disturbances, and periodic disturbances.

TECHNICAL FIELD

The present invention relates to a dynamometer system, particularly tovibrational control in a drivetrain bench, and to a control device and acontrol method for reproducing, with the shaft torque of a dynamometer,a complicated torque waveform in which pulses occur, as in an engine.

BACKGROUND ART

Non-Patent Document 1 discloses a system for controlling vibrationamplitudes while implementing resonance suppression and low-frequencytorque control in a drivetrain bench.

Patent Documents 1 and 2 disclose methods for performing vibrationalcontrol while implementing periodic disturbance suppression control inconsideration of mechanical resonance.

In measurement control systems, such as dynamometer systems, for testingautomobiles and automotive components, it is necessary not only toachieve stability of control, but also to simultaneously satisfyhigh-level demands such as those for high speed, high response, highcapacity and high precision. As one type of hardware for satisfyingthese demands, a low-inertia motor that achieves high speeds and highresponse is sometimes used, forming a multiple-inertia resonance systemtogether with the test piece. In such cases, shaft torsion resonanceeffects tend to occur at the locations for detection of shaft torque,which is the value being measured.

Additionally, periodic disturbances known as torque ripples tend tooccur as a result of the circumstances of electromagnetic design andreductions in the number of motor poles due to specs-based andstructural limitations. Such resonance and disturbances causesignificant problems in testing and measuring devices, so it isessential to implement resonance suppression control and disturbancesuppression control.

In particular, in drivetrain benches for testing vehicle drive systemcomponents such as various types of transmissions and torque convertersin automobiles, it is necessary to simulate engine explosion torquewaveforms by means of a motor drive system, and shaft torque vibrationalcontrol must be implemented across a wide range of frequency bands fromthe low-frequency region to the high-frequency region.

As a result thereof, resonance frequencies that occur in the mechanicalsystem are included in the control band, thus requiring sophisticatedshaft torque control in which the mechanical resonance is suppressedwhile also generating desired vibrational control components.

Non-Patent Document 1 discloses a shaft torque vibrational controlmethod for a drivetrain bench. In a drivetrain bench, there is alow-frequency resonance point and a high-frequency resonance point. Thelow-frequency resonance is caused by nonlinear spring behavior in thetorque converter, which is the test piece, and the high-frequencyresonance is caused by rigidity in the drive motor, the shaft torquemeter, and the mechanical system for coupling the above.

In order to simulate the vibrational torque in an engine, in shafttorque vibrational control, control is required so as to be able toobtain the desired vibration amplitude while suppressing the enlargementof vibrations due to the abovementioned mechanical resonance.

Therefore, in Non-Patent Document 1, a shaft torque control method basedon I-PD control is applied to low-frequency control, which dependslargely on the nonlinear properties of the test piece, and resonancesuppression control based on μ-synthesis is applied to thehigh-frequency resonance caused by the dynamometer equipment.

The document discloses a method for automatically adjusting thevibration amplitude so as to obtain a desired vibration amplitude forthe shaft torque while implementing control in which these frequencybands are separated and combined.

However, this method is limited to vibrational control by a singlefrequency component, i.e. by a sine wave, and only the amplitude of thatsine wave is controlled. Therefore, the phase of the sine wave is notcontrolled.

Furthermore, the actual explosion torque waveform of an engine is adistorted waveform in which multiple frequency components are mixed.Thus, in order to more precisely simulate engine explosion torque, it isnecessary to simultaneously apply vibrations having multiple frequencycomponents and to match not only the amplitude, but also the phase. Thismethod in Non-Patent Document 1 is not able to achieve shaft torquevibrational control that simulates engine explosion torque includingdistortion components.

Additionally, while torque ripples that are generated as a result ofmotor structures exist as periodic disturbances, the periodicdisturbances cannot be adequately suppressed by means of only resonancesuppression control such as μ-synthesis, and they mix with the frequencycomponents due to vibrational control, making shaft torque control morecomplicated. This Non-Patent Document 1 does not take the effects ofsuch periodic disturbances into consideration. Thus, even if a sine-wavevibrational torque command is provided, unintended distortions willoccur in the shaft torque, at frequency components different from thosein the engine waveform.

In Patent Documents 1 and 2, the distortion components included in theengine explosion torque are also considered, and multiple periodiccomponents are controlled by means of a generalized periodic disturbanceobserver. In order to suppress mechanical resonance, inverse propertiesof the torque transfer properties obtained by means of preliminarysystem identification are used, and they are installed as a resonancesuppression table. As a result thereof, the influence of mechanicalresonance and periodic disturbances (torque ripples) can be eliminatedwhile leaving the vibration components in the respective frequencycomponents.

However, the methods disclosed in Patent Documents 1 and 2 are forcontrolling only preset frequency components. Thus, the resonancesuppression table only removes the influence of resonance that is due tothe superimposition of applied vibration frequency components on thetorque command value.

Therefore, when non-periodic disturbances such as torque sensordetection noise and the like are included, the influence of mechanicalresonance remains in the shaft torque detection. Additionally, asidefrom the resonance suppression table, a system identification table forsuppressing periodic disturbances is also necessary, so the amount ofcomputation and amount of memory increase.

As mentioned above, a problem in shaft torque vibrational control ofmotor drive systems is that of tracking engine vibrational torquecommand values including distortion components while entirely removingthe influence of resonance, non-periodic disturbances, and periodicdisturbances.

RELATED ART Patent Documents

Patent Document 1: IP 2011-176950 A

Patent Document 2: JP 2011-176951 A

Non-Patent Documents

Non-Patent Document 1: Akiyama, Ogawa, Sawada and Yamamoto, “ShaftTorque Vibration Control of Drivetrain Bench”, IEEJ Transactions onElectronics, Information and Systems, Vol. 134, No. 7, pp. 909-916,2014.

SUMMARY OF INVENTION

The present invention was proposed in consideration of theaforementioned conventional problem, and in one embodiment thereof, ischaracterized by being a motor drive system for controlling a shafttorque in a motor by using an inverter, wherein the motor drive systemcomprises a low-frequency torque controller for outputting alow-frequency torque controller output based on a torque command valueand a torque detection value; a vibrational torque controller foroutputting a vibrational torque command value based on the torquecommand value, the torque detection value, and a rotational phasedetection value; and a high-frequency resonance suppression controllerfor outputting an inverter torque command value based on the torquedetection value and a corrected torque command value obtained by addingthe low-frequency torque controller output to the vibrational torquecommand value.

Additionally, one embodiment thereof is characterized in that thehigh-frequency resonance suppression controller has a μ-synthesiscontroller for adding an output obtained by subjecting the correctedtorque command value to transfer properties from a μ-synthesiscontroller command value input to a μ-synthesis controller output, to anoutput obtained by subjecting the torque detection value to transferproperties from a μ-synthesis controller detection value input to aμ-synthesis controller output, and outputting an inverter torque commandvalue; and the low-frequency torque controller implements PID control.

Additionally, one embodiment thereof is characterized in that thevibrational torque controller comprises a vibration frequency componentextractor for outputting an nth-order frequency component vector of thevibrational torque command value based on the torque command value andan nth-order rotational phase obtained by multiplying, with therotational phase detection value, an order n of a torque ripplefrequency component and a vibration frequency component to becontrolled; a ripple suppression frequency component extractor foroutputting an nth-order frequency component vector of periodicdisturbances based on the torque detection value and the nth-orderrotational phase; a speed converter for outputting an nth-orderrotational frequency based on the nth-order rotational phase; a firstinverse model multiplication unit for multiplying, with an nth-orderfrequency component vector of the vibrational torque command value, aninverse model to which a single frequency vector synchronized with thenth-order rotational frequency has been applied, and outputting annth-order frequency component vector of a vibration-induced periodicdisturbance command value; a second inverse model multiplication unitfor multiplying, with an nth-order frequency component vector of theperiodic disturbances, an inverse model to which a single frequencyvector synchronized with the nth-order rotational frequency has beenapplied, and outputting an nth-order frequency component vector of anoperation amount estimate value; a first subtractor for subtracting,from the nth-order frequency -component vector of the operation amountestimate value, a value obtained by passing an nth-order frequencycomponent vector of the vibrational torque controller output through alow-pass filter, and output ting an nth-order frequency component vectorof the periodic disturbance estimate value; a second subtractor forsubtracting, from the nth-order frequency component vector of thevibration-induced periodic disturbance command value, the nth-orderfrequency component vector of the periodic disturbance estimate value,and outputting an nth-order frequency component vector of thevibrational torque controller output; and a compensation signalsynthesis unit for outputting the vibrational torque command value basedon the nth-order frequency component vector of the vibrational torquecontroller output and the nth-order rotational phase.

Additionally, one embodiment thereof is characterized in that thevibrational torque controller comprises a third subtraction unit forcalculating a torque deviation between the torque command value and thetorque detection value; a frequency component extractor for outputtingan nth-order frequency component vector of periodic disturbances basedon the torque deviation and an nth-order rotational phase obtained bymultiplying, with the rotational phase detection value, an order n of atorque ripple frequency component and a vibration frequency component tobe controlled; a speed converter for outputting an nth-order rotationalfrequency based on the nth-order rotational phase; an inverse modelmultiplication unit for multiplying, with the nth-order frequencycomponent vector of the periodic disturbances, an inverse model to whicha single frequency vector synchronized with the nth-order rotationalfrequency has been applied, and outputting an nth-order frequencycomponent vector of an operation amount estimate value; an adder foradding the nth-order frequency component vector of the operation amountestimate value to a value obtained by passing an nth-order frequencycomponent vector of the vibrational torque controller output through alow-pass filter, and outputting the nth-order frequency -componentvector of the vibrational torque controller output; and a compensationsignal synthesis unit for outputting the vibrational torque commandvalue based on the nth-order frequency component vector of thevibrational torque controller output and the nth-order rotational phase.

Additionally, one embodiment thereof is characterized in that thevibrational torque controller comprises a third subtraction unit forcalculating a torque deviation between the torque command value and thetorque detection value; a frequency component extractor for outputtingan nth-order frequency component vector of periodic disturbances basedon the torque deviation and an nth-order rotational phase obtained bymultiplying, with the rotational phase detection value, an order n of atorque ripple frequency component and a vibration frequency component tobe controlled; a speed converter for outputting an nth-order rotationalfrequency based on the nth-order rotational phase; an inverse modelmultiplication unit for multiplying, with the nth-order frequencycomponent vector of the periodic disturbances, an inverse model to whicha single frequency vector synchronized with the nth-order rotationalfrequency has been applied, and determining an nth-order frequencycomponent vector of an operation amount estimate value; an integratorfor integrating the nth-order frequency component vector of theoperation amount estimate value, and outputting the nth-order frequencycomponent vector of the vibrational torque controller output; and acompensation signal synthesis unit for outputting the vibrational torquecommand value based on the nth-order frequency component vector of thevibrational torque controller output and the nth-order rotational phase.

Additionally, one embodiment thereof is characterized in that thevibrational torque controller comprises a vibration frequency componentextractor for outputting an nth-order frequency component vector of thevibrational torque command value based on the torque command value andan nth-order rotational phase obtained by multiplying, with therotational phase detection value, an order n of a torque ripplefrequency component and a vibration frequency component to becontrolled; a ripple suppression frequency component extractor foroutputting an nth-order frequency component vector of periodicdisturbances based on the torque detection value and the nth-orderrotational phase; a speed converter for outputting an nth-orderrotational frequency based on the nth-order rotational phase; a firstinverse model multiplication unit for multiplying, with an nth-orderfrequency component vector of the vibrational torque command value, aninverse model to which a single frequency vector synchronized with thenth-order rotational frequency has been applied, and outputting annth-order frequency component vector of a vibration-induced periodicdisturbance command value; a second inverse model multiplication unitfor multiplying, with an nth-order frequency component vector of theperiodic disturbances, an inverse model to which a single frequencyvector synchronized with the nth-order rotational frequency has beenapplied, and outputting an nth-order frequency component vector of anoperation amount estimate value; a first multiplier for multiplying anobserver gain with the nth-order frequency component vector of thevibration-induced periodic disturbance command value and outputting aresult to a second multiplier; a second multiplier for multiplying anobserver gain with the nth-order frequency component vector of theoperation amount estimate value and outputting a result to a firstsubtractor; a first subtractor for subtracting, from the output of thesecond multiplier, a value obtained by passing an nth-order frequencycomponent vector of the vibrational torque controller output through alow-pass filter, and outputting an nth-order frequency component vectorof the periodic disturbance estimate value; a second subtractor forsubtracting, from the output of the first multiplier, the nth-orderfrequency component vector of the periodic disturbance estimate value,and outputting an nth-order frequency component vector of thevibrational torque controller output; and a compensation signalsynthesis unit for outputting the vibrational torque command value basedon the nth-order frequency component vector of the vibrational torquecontroller output and the nth-order rotational phase.

Additionally, one embodiment thereof is characterized in that thevibrational torque controller comprises a third subtraction unit forcalculating a torque deviation between the torque command value and thetorque detection value; a frequency component extractor for outputtingan nth-order frequency component vector of periodic disturbances basedon the torque deviation and an nth-order rotational phase obtained bymultiplying, with the rotational phase detection value, an order n of atorque ripple frequency component and a vibration frequency component tobe controlled; a speed converter for outputting an nth-order rotationalfrequency based on the nth-order rotational phase; an inverse modelmultiplication unit for multiplying, with the nth-order frequencycomponent vector of the periodic disturbances, an inverse model to whicha single frequency vector synchronized with the nth-order rotationalfrequency has been applied, and outputting an nth-order frequencycomponent vector of an operation amount estimate value; a multiplier formultiplying an observer gain with the nth-order frequency componentvector of the operation amount estimate value, and outputting a resultto an adder; an adder for adding the output of the multiplier to a valueobtained by passing the nth-order frequency component vector of thevibrational torque controller output through a low-pass filter, andoutputting the nth-order frequency component vector of the vibrationaltorque controller output; and a compensation signal synthesis unit foroutputting the vibrational torque command value based on the nth-orderfrequency component vector of the vibrational torque controller outputand the nth-order rotational phase.

Additionally, one embodiment thereof is characterized in that thevibrational torque controller comprises a third subtraction unit forcalculating a torque deviation between the torque command value and thetorque detection value; a frequency component extractor for outputtingan nth-order frequency component vector of periodic disturbances basedon the torque deviation and an nth-order rotational phase obtained bymultiplying, with the rotational phase detection value, an order n of atorque ripple frequency component and a vibration frequency component tobe controlled; a speed converter for outputting an nth-order rotationalfrequency based on the nth-order rotational phase; an inverse modelmultiplication unit for multiplying, with the nth-order frequencycomponent vector of the periodic disturbances, an inverse model to whicha single frequency vector synchronized with the nth-order rotationalfrequency has been applied, and determining an nth-order frequencycomponent vector of an operation amount estimate value; a multiplier formultiplying an observer gain with the nth-order frequency componentvector of the operation amount estimate value and outputting a result toan integrator; an integrator for integrating the output of themultiplier, and outputting an nth-order frequency component vector ofthe vibrational torque controller output; and a compensation signalsynthesis unit for outputting the vibrational torque command value basedon the nth-order frequency component vector of the vibrational torquecontroller output and the nth-order rotational phase.

Additionally, one embodiment thereof is characterized by having multiplevibrational torque controllers of different orders n; wherein a valueobtained by summing the outputs of each of the vibrational torquecontrollers is used as the vibrational torque command value.

Additionally, one embodiment thereof is characterized in that, when thenth-order rotational phase is not inputted to the vibration frequencycomponent extractor and a phase that is not synchronized with thenth-order rotational phase is inputted, unsynchronized vibrationfrequency components and nth-order rotational frequencies inparallel-stage control structures are separately monitored, and whenthese frequencies match, the nth-order frequency component vectors ofthe operation amount estimate values in the control structures inmatching stages are set to zero.

Additionally, one embodiment thereof is characterized in that the ordern of the vibrational torque controller includes decimal numbers.

Additionally, one embodiment thereof is characterized by comprising adrive motor for simulating engine explosion torque, connected to aninput side of a test piece; an absorption motor for simulating a loadfrom wheels and a road surface, connected to an output side of the testpiece; a vibrational controller for outputting a first inverter torquecommand value based on a torque detection value and a rotational phasedetection value of the drive motor; a speed controller for outputting asecond inverter torque command value based on the motor rotation speedof the absorption motor; a drive motor inverter for driving the drivemotor based on the first inverter torque command value; and anabsorption motor inverter for driving the absorption motor based on thesecond inverter torque command value.

Thus, according to the present invention, it is possible to provideshaft torque vibrational control of a motor drive system wherein enginevibrational torque command values including distortion components aretracked while entirely removing the influence of resonance, non-periodicdisturbances, and periodic disturbances.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a basic configuration diagram of a drivetrain bench.

FIG. 2 is a diagram showing an example of the frequency transferproperties from the inverter torque command value τ_(inv)* to the torquedetection value τ_(det).

FIG. 3 is a diagram showing an example of the nonlinear springproperties of a test piece.

FIG. 4 is a diagram showing a three-inertia approximation model for acontrol target.

FIG. 5 is a basic control configuration diagram for Embodiment 1.

FIG. 6 is a diagram showing an example of the configuration of ageneralized plant.

FIG. 7 is a property diagram for a μ-synthesis controller.

FIG. 8 is a configuration diagram for a μ-synthesis controller.

FIG. 9 is a frequency transfer property diagram for the case in whichonly high-frequency resonance suppression is implemented.

FIG. 10 is a design diagram for a low-frequency torque controller.

FIG. 11 is a frequency transfer property diagram for the case in whichonly low-frequency torque control is implemented.

FIG. 12 is a frequency transfer property diagram from a vibrationaltorque command value τ_(pd)* to a torque detection value ξ_(det)(low-frequency torque control ON, high-frequency resonance suppressioncontroller ON).

FIG. 13 is a basic configuration diagram showing a vibrational torquecontroller.

FIG. 14 is a diagram showing an example of the effects of Embodiment 1.

FIG. 15 is a configuration diagram showing a vibrational torquecontroller according to Embodiment2.

FIG. 16 is a configuration diagram showing a vibrational torquecontroller according to Embodiment 3.

FIG. 17 is a configuration diagram showing a vibrational torquecontroller according to Embodiment 4.

FIG. 18 is a diagram showing the robust stability of a generalizedperiodic disturbance observer against model error.

FIG. 19 is a diagram showing a torque waveform tracking control examplefor a one-cylinder-misfiring mode.

MODES FOR CARRYING OUT THE INVENTION

The present application proposes “arbitrary waveform tracking control ofwaveforms including distorted waveforms”, so it is not limited to thebasic configuration in FIG. 1. However, for the purposes of Embodiments1 to 7, the solution to the problem and the effects of applying theinvention will be described using an example of implementation inarbitrary waveform tracking control of shaft torque vibrations in abasic configuration similar to the drivetrain bench described inNon-Patent Document 1.

FIG. 1 is a basic configuration diagram showing a drivetrain bench. Thetest piece 1 is a torque converter, and a drive motor 2 on the inputside thereof is used to simulate engine explosion torque. On the outputside, an absorption motor 3 for simulating the load from wheels and aroad surface is provided, and in the present configuration, rotationspeed control is implemented. A shaft torque meter 4 is provided betweenthe test piece 1 and the drive motor 2, and a detected torque detectionvalue τ_(det) is controlled so as to track a torque command value τ*simulating engine explosion torque.

A vibrational controller 5 implements vibrational control based on atorque command value τ* including a vibration frequency component. Inthe present invention, unlike in Non-Patent Document 1, a rotationalphase detection value θ from a rotational position sensor 6 is used todetect the phase of the vibration frequency component.

The speed controller 7 controls the motor rotation speed ω_(m) of therotation position sensor 8 so as to track a speed command value ω_(m)*in order to perform rotation speed control with the absorption motor 3.The speed controller 7 may be implemented by using general PID controlor the like.

The drive motor 2 and the absorption motor 3 are driven, by means of adrive motor inverter INV1 and an absorption motor inverter INV2, basedon inverter torque command values τ_(inv1)* and τ_(inv2)* outputted bythe vibrational controller 5, and the speed controller 7.

The drive motor inverter INV1 and the absorption motor inverter INV2,are power converters for converting DC power to AC power. The AC outputterminals of the drive motor inverter INV1 and the absorption motorinverter INV2 are connected to terminals of the drive motor 2 and theabsorption motor 3. The drive motor inverter INV1 and the absorptionmotor inverter INV2 have the functions of controlling the shaft torques(torque detection values) τ_(det) of the motors to the the invertertorque command values τ_(inv1)* and τ_(inv2)* by controlling the ACoutput currents (i.e., the motor currents) of the drive motor inverterINV1 and the absorption motor inverter INV2.

FIG. 2 is an example of the frequency transfer properties from theinverter torque command value τ_(inv1)* inputted in the drive motorinverter INV1 to the torque detection value τ_(det). In the presentinvention, the configuration in FIG. 1 is approximated by an equivalentthree-inertia system, and the resonance point that varies in thelow-frequency region is generated as a result of the nonlinear springbehavior of the torque converter which is the test piece 1.

For reference, an example of nonlinear spring properties is shown inFIG. 3. The resonance point in the high-frequency region is generated asa result of shaft torsional rigidity in the mechanical equipment such asthe drive motor 2, the shaft torque meter, and couplings.

Thus, the drivetrain bench described in the present invention forms athree-inertia system having nonlinear resonance properties in thelow-frequency region and having high resonance properties in thehigh-frequency region. This means that, when a simple vibrational torqueis applied to the torque command value τ*, resonance will occur and adesired vibration waveform will not be obtained.

In the four-cycle engines that are widely used in automobiles, theexplosion torque thereof includes large torque vibrations at frequencycomponents equal to the number of cylinders×0.5×rotation speed. Forexample, if three-cylinder to eight-cylinder engines are to be simulatedat engine rotation speeds of 600 min⁻¹ to 6000 min⁻¹, vibrationalcontrol must be implemented in the band from 15 to 400 Hz.

Additionally, if distortion components are to be considered, then thecontrol must extend to bands even higher than 400 Hz, so it is necessaryto track vibrational frequency components up to the mechanicalstructural limit as much as possible.

FIG. 4 shows a block diagram of a control target when the presentconfiguration is approximated as a three-inertia system. The referencesigns in FIG. 4 are defined as follows: J1, moment of inertia of drivemotor; J2, moment of inertia of test piece and coupling; J3, moment ofinertia of absorption motor; K12, shaft torsional rigidity of couplingand shaft torque meter; K23 and ΔK23, shaft torsional rigidity of testpiece (having nonlinear properties. FIG. 3); C23, loss in test piece;G_(inv)(s), drive-side inverter response transfer function; G_(tm)(s),shaft torque detection response transfer function; G₀(s), rotationalphase detection response transfer function; s, Laplace operator.

As mentioned above, the torque converter which is the test piece 1 hasnonlinear spring properties, and is thus expressed by using K23 andΔK23. Additionally, the inverter, torque meter detection, and phasedetection involve response delays and lost time, so an approximateresponse transfer function is inserted.

While the frequency transfer properties, from the inverter torquecommand value τ_(inv)* to the torque detection value τ_(det), of theapproximation model shown in FIG. 4 are as shown in FIG. 2, it isdesirable to design a controller in which the gain is always 0 dB, i.e.,the transfer properties from the inverter torque command value τ* to thetorque detection value τ_(det) are 1, in the frequency band in which thevibrations are applied. In order to do so, it is necessary to implementresonance suppression control in the low-frequency region and thehigh-frequency region. Additionally, amplification is necessary in bandsin which the amplitude properties are lower than 0 dB.

Embodiment 1

The present Embodiment 1 is based on a method wherein, as in Non -PatentDocument 1, the frequencies are divided between low-frequency andhigh-frequency resonance frequency bands, and high-frequency resonancesuppression control and low-frequency steady -state torque control areimplemented. This is combined with a generalized periodic disturbanceobserver as a method for implementing “vibration waveform trackingcontrol of waveforms including distortion components”, which cannot beimplemented with the method in Non-Patent Document 1.

FIG. 5 is a control configuration diagram that is based on the presentEmbodiment 1. The reference signs in FIG. 5 are defined as follows:

τ*, torque command value; τ_(dc)*, low-frequency torque controlleroutput; τ_(pd)*, vibrational torque command value; τ_(r)*, correctedtorque command value; τ_(inv)*, inverter torque command value; τ_(det),torque detection value; 0, rotational phase detection value.

As shown in FIG. 5, in the motor drive system for controlling the motorshaft torque in the present Embodiment 1 by using an inverter, alow-frequency torque controller 9 outputs a low-frequency torquecontroller output τ_(dc)* based on a torque command value τ* and atorque detection value τ_(det). Additionally, a vibrational torquecontroller 11 outputs a vibrational torque command value τ_(pd)* basedon the torque command value τ*, the torque detection value τ_(det), anda rotational phase detection value θ. A high-frequency resonancesuppression controller 10 outputs an inverter torque command valueτ_(inv)* based on the torque detection value τ_(det), and a correctedtorque command value τ_(r) * obtained by adding the low-frequency torquecontroller output τ_(dc)* to the vibrational torque command valueτ_(pd)*.

The “control target” in the present Embodiment 1 corresponds to thethree-inertia approximation model shown in FIG. 4.

As shown in FIG. 5, the functions of the present Embodiment 1 includethe three functions of a “low-frequency torque controller 9”, a“high-frequency resonance suppression controller 10”, and a “vibrationaltorque controller 11” formed by a generalized periodic disturbanceobserver. Herebelow, each function will be described in order.

First Function, “High-Frequency Resonance Suppression Controller 10”

In the three-inertia approximation model shown in FIG. 4, there is alow-frequency resonance point and a high-frequency resonance point. Whena comprehensive controller that implements resonance suppression acrossall frequency bands is designed, the design tends to be conservative,and when taking nonlinearities in the low-frequency region intoconsideration, it becomes difficult to design systems that have robustcontrol performance.

Therefore, in such a system, it is effective to separate low-frequencyand high-frequency control systems. In the present Embodiment 1,high-frequency resonance suppression control is implemented by aμ-synthesis controller which is a robust control method, and this iscombined with a method in which the low-frequency nonlinear resonanceproperties due to the test piece 1 are not subjected to active resonancesuppression control, and steady-state torque tracking control isimplemented.

First, the high-frequency resonance suppression controller 10, which isthe first function, will be explained. The resonance frequency in thehigh-frequency region, based on the properties in FIG. 2, is equivalentto the resonance frequency in the two-inertia resonance system with themoment of inertia J1 of the drive motor and the moment of inertia J2 ofthe test piece and the coupling in FIG. 4. Therefore, the high-frequencyresonance frequency is roughly the same as the resonance frequencyf_(rH) calculated by Equation (1).

[Expression  1] $\begin{matrix}{f_{rH} = {\frac{1}{2\pi}\sqrt{K\; 12\left( {\frac{1}{J\; 1} + \frac{1}{J\; 2}} \right)}}} & (1)\end{matrix}$

Therefore, taking into account this approximated two-inertia system inorder to suppress the high-frequency resonance, a generalized plant usedfor designing a high-frequency resonance suppression controller isformed as shown in FIG. 6. In the present Embodiment 1, an example usingμ-synthesis, which is a robust control method, will be described, but itis possible to use other general resonance suppression control methods,such as H_(∞) control. The reference signs in FIG. 6 are defined asfollows:

Δτ, torque deviation; G_(tm)(s), detection response transfer function oftorque meter or the like; G_(inv)(s), inverter response transferfunction; d1, disturbance (including periodic disturbances); d2 and r,μ-synthesis controller command value inputs; d3, torque detection noise;z, steady-state torque error evaluation output; w, disturbance input dueto steady-state torque error; u, μ-synthesis controller output; y,μ-synthesis controller detector input; e1, torque detection valueevaluation output; e2, inverter torque command evaluation output; e3,μ-synthesis controller gain evaluation output; W_(n)(s), weightingfunction for disturbance d1; W_(n)(s), weighting function forii-synthesis controller output u; W_(e)(s), weighting function forμ-synthesis controller gain.

When designing a controller using μ-synthesis, perturbations in themechanical parameters or the like could be separately considered.However, in practice, the explicit identification of a physical model(spring/mass elements) is often omitted in favor of simplifiedidentification based on the frequency transfer properties from thetorque inputs and outputs.

Therefore, in this case, a method in which the torque error Ax inputtedfrom the inverter is approximated as the perturbation term is used toensure robust control performance.

In order to implement steady-state torque tracking control in thelow-frequency region using the low-frequency torque controller 9mentioned below, the high-frequency resonance suppression controller 10in the high-frequency region is designed so as to reduce the controllergain in the low-frequency region.

In other words, in the gain from the command value input r of theμ-synthesis controller to the μ-synthesis controller output u, aμ-synthesis controller gain evaluation output e3 is set by means of aweighting function W_(e)(s) on the μ-synthesis controller gain. In orderto prevent control interference with the low-frequency torque controller9, the weighting function W_(e)(s) on the μ-synthesis controller gain isweighted in the low-frequency region.

Additionally, the weighting function W_(u)(s) for the μ-synthesiscontroller output u (weighting function for the inverter torque commandu) is weighted in the high-frequency region so as to reduce thehigh-frequency gain of the inverter torque command. The weightingfunction W_(n)(s) for the disturbance d1 is weighted in the vicinity ofthe resonance frequency in order to improve the periodic disturbance andnon-periodic disturbance suppression performance.

An example of the properties of a μ-synthesis controller obtained byperforming D-K iteration in a generalized plant configured as in FIG. 6is shown in FIG. 7. As can be understood by seeing the gain propertiesin the transfer properties C_(tm)(s), the low-frequency gain is loweredso as not to respond to the torque detection value τ_(det) on thelow-frequency (low frequency region) side due to the effects of theweighting function W_(e)(s) on the μ-synthesis controller gain. As aresult thereof, it is possible to prevent control interference with thelow-frequency torque controller 9 described below.

Additionally, as can be understood by seeing the gain properties in thetransfer properties C_(ref)(s), the controller is designed to reduce thegain in the vicinity of the resonance frequency, so resonance due to thefrequency component of the vibrational torque can be suppressed.

In FIG. 7, the upper part shows a gain diagram and the lower part showsa phase diagram. The left side shows the transfer properties C_(ref)(s)of the μ-synthesis controller from the command value input r to theμ-synthesis controller output u, and the right side shows the transferproperties C_(tm)(s) of the μ-synthesis controller from the detectionvalue input y to the μ-synthesis controller output u.

The μ-synthesis controller having the transfer properties C_(ref)(s) andthe transfer properties C_(tm)(s) designed above is installed, with theconfiguration shown in FIG. 8, in a portion of the high-frequencyresonance suppression controller 10 in FIG. 5.

An output obtained by subjecting the corrected torque command valueτ_(r)* to the transfer properties C_(ref)(s) is added to an outputobtained by subjecting the torque detection value τ_(det) to thetransfer properties C_(tm)(s) so as to generate an inverter torquecommand value τ_(inv)*.

FIG. 9 shows the frequency transfer properties from the torque commandvalue τ* to the torque detection value τ_(det) for the case in whichonly high-frequency resonance suppression control is implemented. It canbe seen that the high-frequency (high-frequency region) gain issuppressed to 0 dB or less.

Second Function, “Low-Frequency Torque Controller 9”

Next, the low-frequency torque controller 9 in FIG. 5 will be describedas the second function. The resonance frequency in the low-frequencyregion varies depending on the nonlinear spring properties of the testpiece 1. A method of implementing robust resonance suppression controltaking these nonlinear properties into consideration could becontemplated, but the design would depend on the nonlinear properties ofthe test piece. In actual practice, tests are often run by exchangingthe test piece 1, and if the controller were to be designed so as todepend on the properties of the test piece, then there would be aproblem in that the controller or the parameters thereof would need tobe readjusted each time.

Therefore, the present Embodiment 1 aims for a design that does notdepend on the properties of the test piece 1 even if it is changed, sothat the low-frequency torque controller 9 does not actively performsuppression control, and merely has the purpose of providing stabletracking control of the steady-state torque.

In the three-inertia approximation model shown in FIG. 4, by focusing onthe resonance frequency in the low-frequency region, it is possible toapproximate the model as a two-inertia resonance system with theparameters J1+J2, K23, and J3, in view of the properties in FIG. 2. Inother words, the resonance frequency f_(rL) in the low-frequency regionis roughly given by Equation (2). However, the influence of the shafttorsional loss C23 is omitted.

[Expression  2] $\begin{matrix}{f_{rL} = {\frac{1}{2\pi}\sqrt{K\; 23\left( {\frac{1}{{J\; 1} + {J\; 2}} + \frac{1}{J\; 3}} \right)}}} & (2)\end{matrix}$

When a low-frequency control target is approximated as a two-inertiasystem, a low-frequency torque controller 9 can be designed by using anapproximation as shown in FIG. 10. As one example, the controlleremploys a format wherein

proportion-derivative-forward I-PD control based on PID control is used,and a first -order low-pass filter G_(F1)(s) is applied to theproportion term and the derivative term. Of course, the controller isnot limited to the configuration in FIG. 10 and may be realized by usingother types of PID control.

Additionally, in order to avoid control spillover due to thehigh-frequency resonance point, a second-order low-pass filter G_(F2)(s)is used on the output of the I-PD controller. The cutoff frequency ofthis second-order low-pass filter G_(F2)(s) is set to be a cutofffrequency that does not largely influence the low-frequency torquecontrol properties and that can cut off the high-frequency resonanceproperties. As a result thereof, the control is separated from that ofthe high-frequency resonance suppression control system which is theabove-described first function, thereby preventing control interference.

The closed-loop transfer properties from the torque command value τ* tothe torque detection value τ_(det) in the configuration approximated inFIG. 10 are fourth-order properties, so the parameters K_(p), K_(i) andK_(d) in the I-PD control may be calculated by using a model matchingmethod for matching the poles in a fourth-order standard model. As anexample, when the poles are arranged with the properties of afourth-order Butterworth filter, the parameters are calculated as shownin Equation (3). The method for determining the PID parameters is notlimited thereto, and they may be adjusted using various other methods.

[Expression  3] $\begin{matrix}\left\{ \begin{matrix}{K_{p} = {\frac{{J\; 1} + {J\; 2} + {J\; 3}}{J\; 3} \cdot \left( {\frac{k^{2}\left( {{a_{1}a_{3}} - 1} \right)}{a_{3}^{2}} - 1} \right)}} \\{{K_{i} = {\frac{{J\; 1} + {J\; 2} + {J\; 3}}{J\; 3} \cdot \frac{\omega_{0}k^{2}}{a_{3}}}}\mspace{146mu}} \\{{K_{d} = {\frac{{J\; 1} + {J\; 2} + {J\; 3}}{J\; 3} \cdot \frac{{a_{2}k^{2}} - 1}{a_{3}\omega_{0}}}}\mspace{104mu}} \\{{\omega_{f\; 1} = {a_{3}\omega_{0}}}\mspace{301mu}}\end{matrix} \right. & (3)\end{matrix}$

a1, a2, and a3 are the coefficients of the respective orders in theequation for the properties determined by the pole arrangement in thestandard model. In the case of a Butterworth standard, a1=2.6131,a2=3.4142 and a3=2.6131.

Additionally, k is a parameter for determining the control response fortorque tracking control, and is designated by a coefficient to thelow-frequency resonance frequency f_(rL). In this case, the responsefrequency ωc is determined by ωc=k×(2×τ×f_(rL)). ωf1 is the cutofffrequency of the low-pass filter associated with the proportion term andthe derivative term, and can be determined as in Equation (3). Thefrequency transfer properties from the torque command value τ* to thetorque detection value τ_(det) when implementing low-frequency torquecontrol configured as indicated above are shown in FIG. 11.

As can be understood by seeing FIG. 11, the low-frequency torquecontroller 9 cuts off the low-frequency resonance properties, but thedesired command value amplitude is obtained only in a frequency regioneven lower than the low-range resonance frequency.

In other words, although it is possible to implement stable trackingcontrol in the region lower than the low-range resonance frequency orthe steady -state torque, the controller will not be able to respondeven when a high-frequency vibration signal is applied to the torquecommand value. Therefore, for vibrational control, it is necessary toseparately use a vibrational torque controller 11 that is not connectedwith the low-frequency torque controller 9, as shown in FIG. 5, and tosuperimpose the result at the output unit of the low-frequency torquecontroller.

Third Function, “Vibrational Torque Controller 11”

As mentioned above, the low-frequency torque controller 9 only performstracking control in the low-frequency region including the steady-statetorque, and the high-frequency resonance suppression controller 10contributes only to attenuate the resonance properties in thehigh-frequency region. Therefore, in order to implement vibrationalcontrol across the desired wide range of frequency bands, thevibrational torque controller 11 in FIG. 5 is necessary.

The vibrational torque controller 11 receives, as inputs, a torquecommand value τ* and a torque detection value τ_(det) includingvibration frequency components, and a reference phase θ (the rotationalphase detection value of the motor) for generating vibration frequencycomponents. A vibrational torque command value τ_(pd)* that is outputtedfrom the vibrational torque controller 11 is superimposed on thelow-frequency torque controller output τ_(dc)*, forming a correctedtorque command value τ_(r)*.

At this time, the transfer properties of the vibrational torquecontroller II from the vibrational torque command value τ_(pd)* to thetorque detection value τ_(det) are the closed-loop transfer propertiesof the control target, including the low-frequency torque controller 9and the high-frequency resonance suppression controller 10, and are asshown in FIG. 12. In the vibrational frequency band, it is desirable forthe amplitude (gain) properties in FIG. 12 to be constantly 0 dB, andfor the phase properties to be constantly 0 degrees. However, it isdifficult to obtain a controller that actually has such frequencyproperties.

Therefore, in the vibrational torque controller 11, it is necessary toadjust the gain and the phase of each frequency component of thevibrational torque by taking into consideration the transfer propertiesin FIG. 12. Although it is possible to generate a command value by usinginverse properties of FIG. 12 in the frequency band (15 to 400 Hz) inwhich the vibrations are applied, the test piece 1 has nonlinear springproperties, which change according to the operating state. Therefore,with a method for generating a command value simply by using inverseproperties, it is difficult to obtain a vibrational torque waveform withthe desired amplitude and phase.

Thus, a method for automatically adjusting the vibrational torquewaveform by using a generalized periodic disturbance observer isproposed. FIG. 13 shows a basic configuration diagram for thevibrational torque controller 11 in the present Embodiment 1. Thereference signs in FIG. 13 are defined as follows:

τ*, torque command value (including the vibration frequency components);τ_(det), torque detection value; θ, rotational phase detection value; n,order (designating the order of the torque ripple frequency componentand the vibration frequency component to be controlled); ω_(m), motorrotation speed; τ_(rpd)*, vibrational torque command value; T_(n)*,nth-order frequency component vector of vibrational torque commandvalue; T_(n) ^({circumflex over ( )}), nth-order frequency componentvector of periodic disturbances (torque ripples); U_(n)^({circumflex over ( )}), nth-order frequency component vector ofoperation amount estimate value (estimate value including periodicdisturbances); D_(n)*, nth-order frequency component vector of vibration-induced periodic disturbance command value; D_(n)^({circumflex over ( )}), nth-order frequency component vector ofperiodic disturbance estimate value; T_(pdn)*, nth-order frequencycomponent vector of vibrational torque controller output; G_(F)s),low-pass filter for extracting frequency components.

A generalized periodic disturbance observer is a control system forsuppressing periodic disturbances by focusing on a specific frequencycomponent, which is applied, in the present Embodiment 1, as a methodfor generating desired periodic vibrations, in this method, the controlsystem contributes only specific frequency components. First, thefrequency component at which vibrations are to be applied is extractedby the vibration frequency component extractor 12, and the frequencycomponent of the periodic disturbances (torque ripples) to be suppressedis extracted by the ripple suppression frequency component extractor 13.

That is, in the vibration frequency component extractor 12, thenth-order frequency component vector T_(n)* of the vibrational torquecommand value is outputted based on the torque command value τ_(n)* andthe nth-order rotational phase nθ obtained by multiplying the rotationalphase detection value θ with the order n. Additionally, in the ripplesuppression frequency component extractor 13, the nth-order frequencycomponent vector T_(n) of the periodic disturbances is outputted basedon the torque detection value τ_(det) and the nth-order rotational phasenθ.

These are nth-order frequency components that are generated insynchronization with the motor rotation speed, and are thus extracted asdescribed below, using the nth-order rotational phase nθ which isn-times the rotational phase detection value θ. In this case,coordinates synchronized with the frequency component of the nth-orderrotational phase nθ are defined as a d_(n)q_(n) rotating coordinatesystem, wherein d_(n) represents the real part of a complex vector andq_(n) represents the axis for the imaginary part.

[Expression  4] $\begin{matrix}{T_{n}^{*} = {\begin{bmatrix}T_{dn}^{*} \\T_{qn}^{*}\end{bmatrix} = {{G_{F}(s)} \cdot {\mathcal{L}\left\lbrack {\begin{bmatrix}{\cos \mspace{14mu} n\; \theta} \\{\sin \mspace{14mu} \theta \; n}\end{bmatrix} \cdot \tau^{*}} \right\rbrack}}}} & (4) \\{T_{n} = {\begin{bmatrix}T_{dn} \\T_{qn}\end{bmatrix} = {2{{G_{F}(s)} \cdot {\mathcal{L}\left\lbrack {\begin{bmatrix}{\cos \mspace{14mu} n\; \theta} \\{\sin \mspace{14mu} n\; \theta}\end{bmatrix} \cdot \tau_{\det}} \right\rbrack}}}}} & (5)\end{matrix}$

where T_(n)*=T_(dn)*+jT_(qn)*, T_(n)=T_(dn)+jT_(qn), L indicates aLaplace transform, and s indicates a Laplace operator.

Equation (4) is for extracting the vibration frequency componentincluded in the torque command value τ* and Equation (5) is forextracting the periodic disturbances included in the torque detectionvalue τ_(det), i.e., the frequency component of the torque ripple.Although a strict Fourier transform may he used, in the presentEmbodiment 1, the frequency components are extracted by a low-passfilter G_(F)(s) in consideration of the ease of installation in thecomputation unit.

In a speed converter 14, the nth-order rotational phase nθ isdifferentiated to compute the nth-order rotational frequency n·ω_(m).

Next, the inverse model Q_(n) will be described. In the d_(n)q_(n)rotating coordinate system, the control system only affects the specificfrequency component, so the control target model in the vibrationaltorque controller 11 can be represented by a one-dimensional complexvector. In this case, the control target model synchronized with thefrequency component of the nth-order rotational phase nθ is defined asP_(n), where P_(n)=P_(dn)+jP_(qn).

As mentioned above, the control target system for the vibrational torquecontroller 11 has the frequency transfer properties from the vibrationaltorque command value τ_(pd)* to the torque detection value τ_(det) shownin FIG. 12. However, the amplitude and phase properties synchronizedwith the frequency component of the nth-order rotational phase nθ inthis graph, extracted as a complex vector, form the control target modelP_(n). Therefore, this means that the control target model P_(n) changesaccording to the motor rotation speed ω_(m) and the order n.

For example, when the amplitude and phase properties from 1 to 1000 Hzin FIG. 12 are divided for every Hz, 1000 complex vectors are formed,and one vector synchronized with the frequency component of thenth-order rotational phase nθ, which changes according to the motorrotation speed, may be selected therefrom, and applied to the controltarget model P_(n). In other words, the control target model P_(n)corresponds to a type of gain scheduling function that is dependent onthe motor rotation speed.

The control target model P_(n) in the d_(n)q_(n) rotating coordinatesystem defined in this way changes in accordance with the frequencycomponent that is to be suppressed or applied as a vibration, and theinverse model Q_(n) thereof must be changed in accordance with the motorrotation speed. Therefore, as shown in FIG. 13, an inverse modelsynchronized with the frequency component of the nth-order rotationalphase nθ is selected on the basis of the nth-order rotational frequencyn·ω_(m) calculated by the speed detector. The inverse model Q_(n) isexpressed by the following Equation (6):

[Expression  5] $\begin{matrix}{Q_{n} = {{Q_{dn} + {j\; Q_{dn}}} = \frac{1}{P_{dn} + {j\; P_{qn}}}}} & (6)\end{matrix}$

The purpose of the present control is to implement desired vibrationaltorque and torque ripple suppression using a shaft torque meter, whichis the output of the control target, and the input (operation amount) tothe control target must be determined by considering the control targettransfer properties (control target model) P_(n). Therefore, as shown inFIG. 13, the properties of the inverse model Q_(n) are used to calculatethe nth- order frequency component vector D_(n)* of thevibration-induced periodic disturbances at the input of the controltarget model P_(n) from the nth-order frequency component vector T_(n)*of the vibrational torque command value. The equation for computing thenth-order frequency component vector D_(n)* of the vibration-inducedperiodic disturbances is Equation (6-2).

[Expression 6]

D* _(n) =Q _(n) ·T* _(n)   (6-2)

Similarly, the nth-order frequency component spectrum T_(n) of theperiodic disturbances is used to estimate the nth-order frequencycomponent vector (estimate value including periodic disturbances) U_(n)^({circumflex over ( )}) of the operation amount estimate value. Theequation for computing the nth-order frequency component vector U_(n)^({circumflex over ( )}) of the operation amount estimate value isEquation (6-3).

[Expression 7]

U _(n) ^({circumflex over ( )}) =Q _(n) ·T _(n)   (6-3)

In this case, the nth-order frequency component vector U_(n)^({circumflex over ( )}) of the operation amount estimate value isestimated so as to include the component of the torque ripples, whichare periodic disturbances. Therefore, the nth-order frequency componentvector T_(pdn)* of the vibrational torque controller output, which isthe operation amount inputted to the control target model P_(n), issubtracted therefrom to estimate the nth-order frequency componentvector D_(n) ^({circumflex over ( )}) of the periodic disturbanceestimate value. These principles follow those of disturbance observermethods that have conventionally been widely used.

When the nth-order frequency component vector T_(pdn)* of thevibrational torque controller output is subtracted from the nth-orderfrequency component vector U_(n) ^({circumflex over ( )}) of theoperation amount estimate value, the nth-order frequency componentvector T_(pdn)* of the vibrational torque controller output that haspassed through the low-pass filter G_(F)(s) is subtracted for thepurpose of synchronization with the response delays in the low-passfilters G_(F)(s) used in the vibrational frequency component extractor12 and the ripple suppression frequency component extractor 13.

Furthermore, the nth-order frequency component vector T_(pdn)* of thevibrational torque controller output is calculated by furthersubtracting the nth-order frequency component vector D_(n)^({circumflex over ( )}) of the periodic disturbance estimate value fromthe nth-order frequency component vector D_(n)* of the vibration-inducedperiodic disturbance command value. Due to the above, it is possible toremove the vibration components due to periodic disturbances (torqueripples) while leaving the frequency components included in thevibrational torque command, allowing only the desired vibrationalcomponents to be generated in the shaft torque detection unit.

In the compensation signal synthesis unit 19, the nth-order frequencycomponent vector T_(pdn)* of the vibrational torque controller output isrestored from the d_(n)q_(n) rotating coordinate system to a timewaveform on the basis of Equation (7). It is also possible to configurethe invention so that there are multiple orders of n arranged inparallel, and these frequency components of each order can be summed tosynthesize a vibrational torque command value τ_(pd)*.

[Expression 8]

τ*_(pd) =T* _(PDdn) cos nq+T* _(PDqn) sin nq   7)

where T _(PDn) *=T _(PDn) *+jT _(PDqn)*

The three basic functions included in the configuration of FIG. 5 havebeen described above. By simultaneously operating these three functions,the following effects are obtained.

The functions of “low-frequency torque tracking control”,“high-frequency resonance suppression control” and “shaft torquevibrational control” operate simultaneously without interference, and itis possible to simulate engine explosion torque, which has a distortedwaveform including multiple frequency components.

It is possible to suppress only periodic disturbances due to torqueripples, which cause problems, while leaving the vibration components ofvibrational torque commands.

By applying high-frequency resonance suppression control, sudden changesin amplitude and phase due to resonance properties can be reduced,thereby also reducing the inverse model properties of the generalizedperiodic disturbance observer in the vibrational torque controller 11.This means that the property changes are reduced when extracting theinverse model during variable-speed operation, which greatly contributesto improvements in robust stability, particularly when the resonancefrequencies intersect or when there is modeling error.

High-frequency resonance suppression control also has the effect ofsuppressing non-periodic disturbances so that, in addition to periodicdisturbance suppression effects using the generalized periodicdisturbance observer, non-periodic disturbances can be simultaneouslysuppressed.

By designing the system so that low-frequency torque tracking control,high-frequency resonance suppression control, and periodic componentcontrol systems are separated, it is possible to simultaneouslyimplement comprehensive “resonance suppression”, “non-periodicdisturbance suppression”, “periodic disturbance suppression”, and“vibrational control”, which it is difficult to realize with the systemsseparately. Additionally, there is no control interference therebetween.

FIG. 14 shows an example of the effects in the present Embodiment 1. Theupper part of FIG. 14 is the shaft torque waveform in a conventionalvibrational control system. This is the case in which “low-frequencytorque control” and “high-frequency resonance suppression control” areapplied as in Non- Patent Document 1, but the “vibrational torquecontroller 11” proposed in the present Embodiment 1 is not made tofunction, and the vibrational torque command value including thedistortion components is applied directly to the vibrational torquecommand value τ_(pd)*. The vibrational torque command value and theshaft torque detection value do not match, and the desired waveform isnot obtained in the shaft torque.

In Non-Patent Document 1, a method for automatically adjusting thevibration amplitude is proposed, but the method tracks only themagnitude of the vibration amplitude, and is premised on vibrationalcontrol by means of a sine waveform having a single frequency component.Therefore, even if the vibration amplitude control in the Non-PatentDocument 1 is implemented, it is not possible to perform trackingcontrol of the shape of the distorted waveform, and the phase is alsounmatched. Additionally, since the effects of periodic disturbances suchas torque ripples are not considered, unwanted distortion componentsremain as indicated by the waveform in the upper part of FIG. 14.

The lower part of FIG. 14 shows a torque waveform for the case in whichengine vibrational torque waveform tracking control is implemented bythe vibrational torque controller 11 in the present Embodiment 1. Thewaveform is matched to the vibrational torque command value includingdistorted waveforms, and is able to track both the amplitude and phase.Additionally, simultaneously with the vibrational control, torqueripples, which are periodic disturbances, are estimated and removed by ageneralized periodic disturbance observer, so unwanted distortions dueto periodic disturbances such as those mentioned above are also removed.

Even if there is a change in the operating state such as the motorrotation speed (corresponding to the engine rotation speed) and themagnitude of the torque, the vibrational torque controller can stillfunction and the shape can be automatically tracked. In this case, thetransient response is the same as the quick response of the generalizedperiodic disturbance observer, and is determined by the low-pass filterGf(s) used in periodic frequency extraction. As a numerical example, itis possible to track even transient changes at approximately 0.3seconds.

When Embodiment 1 is applied to the motor drive system in FIG. 1, thevibrational controller 5 in FIG. 1 is formed from the low-frequencytorque controller 9, the high-frequency resonance suppression controller10, and the vibrational torque controller 11 in FIG. 5.

Embodiment 2

In the configuration of Embodiment 1 shown in FIG. 13, the frequencycomponent included in the torque command value τ* and the periodicdisturbance frequency component included in the torque detection valueτ_(det) were separately extracted. However, in the present Embodiment 2,these are not distinguished, and a method for simultaneously controllingthe vibrational frequency component and the periodic disturbancecomponent using a simpler configuration is provided.

FIG. 15 is a configuration diagram showing a vibrational torquecontroller 11 according to the present Embodiment 2. The other controlfunctions are similar to those in Embodiment 1.

Taking the torque deviation Ax between the torque command value τ*including the vibrational frequency component and the torque detectionvalue τ_(det), if the frequency components contained in the deviationbecome zero, then this means that the vibrational torque command valueand the shaft torque detection value are matched with regard to theperiodic vibrational component.

Therefore, in the present Embodiment 2, the generalized periodicdisturbance observer is operated so as to eliminate the deviation byextracting the frequency component of the torque deviation Δτ in anintegrated manner without distinguishing between the vibrationalfrequency component and the periodic disturbance frequency component dueto torque ripples. In FIG. 13 relating to Embodiment 1, the nth-orderfrequency component vector D_(n)* of the vibration-induced periodicdisturbance command value was used as the command-side frequencycomponent vector. However, since the purpose in the present Embodiment 2is to eliminate the deviation, it is sufficient to set the nth-orderfrequency component vector D_(n)* of the vibration-induced periodicdisturbance command value to zero.

In FIG. 13, the control block diagram, for the case in which thenth-order frequency component vector D_(n)* of the vibration-inducedperiodic disturbance command value is set to zero, can be converted tothe equivalent as in FIG. 15, and the same control effects as inEmbodiment 1 can be obtained with a relatively simple configuration.Compared to FIG. 13 in Embodiment 1, one of the vibrational frequencycomponent extractors 12 and an inverse model multiplier 15 formultiplying the inverse model can be omitted, thereby reducing thecomputation load of a computer such as a microprocessor.

Additionally, by using the torque deviation Δτ, the DC component isremoved, in the steady state, by means of the tracking operation of thelow-frequency torque controller 9. The secondary effects due thereto areexplained below.

If a DC component Tdc is included in the frequency component extractor22, the frequency components T_(dn) and T_(qn) can be expanded as inEquation (8) below.

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Expression}\mspace{14mu} 9} \right\rbrack} & \; \\\left\{ \begin{matrix}\begin{matrix}{T_{dn} = {2{{G_{F}(s)} \cdot {\mathcal{L}\left\lbrack {{\left( {T_{dc} + {T_{dn}\mspace{14mu} \cos \mspace{14mu} n\; \theta} + {T_{qn}\mspace{14mu} \sin \mspace{14mu} n\; \theta}} \right) \cdot \cos}\mspace{14mu} n\; \theta} \right\rbrack}}}} \\{= {{G_{F}(s)} \cdot {\mathcal{L}\left\lbrack \left( {T_{an} + {T_{dn}\mspace{14mu} \cos \mspace{14mu} 2n\; \theta} + {T_{qn}\mspace{14mu} \sin \mspace{14mu} 2n\; \theta} + {2T_{dc}\mspace{14mu} \cos \mspace{14mu} n\; \theta}} \right) \right\rbrack}}}\end{matrix} \\\begin{matrix}{T_{qn} = {2{{G_{F}(s)} \cdot {\mathcal{L}\left\lbrack {{\left( {{T_{dn}\mspace{14mu} \cos \mspace{14mu} n\; \theta} + {T_{qn}\mspace{14mu} \sin \mspace{14mu} n\; \theta}} \right) \cdot \sin}\mspace{14mu} n\; \theta} \right\rbrack}}}} \\{= {{G_{F}(s)} \cdot {\mathcal{L}\left\lbrack \left( {T_{qn} - {T_{qn}\mspace{14mu} \cos \mspace{14mu} 2n\; \theta} + {T_{dn}\mspace{14mu} \sin \mspace{14mu} 2n\; \theta} + {2T_{dc}\mspace{14mu} \sin \mspace{14mu} n\; \theta}} \right) \right\rbrack}}}\end{matrix}\end{matrix} \right. & (8)\end{matrix}$

By removing T_(dn) cos 2nθ+T_(qn) sin 2nθ+2T_(dc) cos nθ and T_(qn) cos2nθ+T_(dn) sin 2nθ +2T_(dc) sin nθ in Equation (8) with a low-passfilter G_(F)(s), T_(dn) and T_(qn) can be obtained. A 2nθ component andan nθ component are included, and if these frequency components aresufficiently higher than the cutoff frequency of the low-pass filterG_(F)(s), then these frequency components can be cleanly extracted.

If the motor rotation speed is low and the frequency of the nth-orderrotational phase nθ is also low, then the cutoff frequency of thelow-pass filter G_(F)(s) will be approached, meaning that the influenceof the frequency components of T_(dn) cos 2nθ+T_(qn) sin 2nθ+2T_(dc) cosnθ and T_(qn) cos 2nθ+T_(dn) sin 2nθ+2T_(dc) sin nθ will appear inT_(dn) and T_(qn). These become disturbances in the d_(n)q_(n) rotatingcoordinate system of the generalized periodic disturbance observer, andcause destabilization of the control system.

Therefore, the cutoff frequency of the low-pass filter G_(F)(s) must beset to a sufficiently low value. However, as mentioned above, thetransient response of the generalized periodic disturbance observer isdetermined by the response of the low-pass filter G_(F)(s). Thus, if thecutoff frequency is made too low, then the quick response of the torquewaveform tracking will become worse.

In order to mitigate this tradeoff, it is desirable to pre-remove the nθcomponent in T_(dn) cos 2nθ+T_(qn) sin 2nθ+2T_(dc) cos nθ and T_(qn) cos2nθ+T_(dn) sin 2nθ+2T_(dc) sin nθ in Equation (8). Focusing on thecoefficients of the sin nθ and cos nθ, it can be seen that both are2·T_(dc). In other words, if the DC component T_(dc) included in theinput signal is zero, then there will be no nθ component. As a resultthereof, only the 2nθ component will remain in T_(dn) cos 2nθ+T_(qn) sin2nθ+2T_(dc) cos nθ and T_(qn) cos 2nθ+T_(dn) sin 2nθ+2T_(dc) sin nθ inEquation (8).

The 2θ component can be more easily cut off than the nθ component, thusmitigating the above-mentioned tradeoff problem, and making it easier todesign a low-pass filter G_(F)(s).

In the present Embodiment 2, the nth-order frequency component vectorT_(n) of periodic disturbances is determined by inputting, to thefrequency component extractor 22, the torque deviation Δτ instead of thetorque detection value τ_(det) in Equation (5). In the presentEmbodiment 2, the DC component of the torque deviation Δτ is eliminatedby the low-frequency torque controller 9, and the input signal to thefrequency component extractor is the torque deviation Δτ, so theaforementioned secondary effects are also obtained.

Embodiment 3

In the present Embodiment 3, the low-pass filter in the frequencycomponent extractor 22 is limited to being a first-order filter, and theconfiguration of Embodiment 2 is further simplified. FIG. 16 is aconfiguration diagram showing the present Embodiment 3.

If the low-pass filter G_(F)(s) used in the frequency componentextractor 22 of the generalized periodic disturbance observer is limitedto being the first-order low-pass filter indicated by Equation (9), FIG.15 showing Embodiment 2 can be converted to the equivalent control blockdiagram in FIG. 16.

[Expression  10] $\begin{matrix}{{G_{F}(s)} = \frac{\omega_{f}}{s + \omega_{f}}} & (9)\end{matrix}$

where ω_(f) is the low-pass filter cutoff frequency

In FIG. 16, the frequency component extractor 22 in FIG. 15 is changedto a frequency component converter 24, and the low-pass filter G_(F)(s)is changed to an integrator 23. In other words, the low-pass filterG_(F)(s) that is inside the frequency component extractor 22 in FIG. 15is moved to the outside. Furthermore, the integrator 23 is a simpleintegrator 23 having a cutoff frequency of ωf and the inverse model asthe gain, obtained as a result of combining the low-pass filter G_(F)(s)inside the frequency component extractor 22 with a latter-stage low-passfilter G_(F)(s). In this way, FIG. 15 can be equivalently converted toFIG. 16. However, the frequency component converter 24 in FIG. 16 usesthe following Equation (10).

[Expression  11] $\begin{matrix}{T_{n}^{*} = {{2 \cdot \begin{bmatrix}{\cos \mspace{14mu} n\; \theta} \\{\sin \mspace{14mu} n\; \theta}\end{bmatrix} \cdot \Delta}\; t}} & (10)\end{matrix}$

Since Equation (10) does not include a low-pass filter G_(F)(s), thenth-order frequency component vector T_(pdn)* of the vibrational torquecontroller output is directly generated without expressly extracting thefrequency component of the periodic disturbances contained in the torquedeviation Δτ.

According to the present Embodiment 3, when the low-pass filter G_(F)(s)is limited to being a first-order filter, a generalized periodicdisturbance observer for the torque deviation can be realized with anextremely simple configuration comprising only an integrator 23 havingωf as the gain. Therefore, in addition to obtaining the effects ofEmbodiment 2, the amount of computation associated with control can befurther reduced.

Embodiment 4

In the present Embodiment 4, a configuration in which the observer gainis added to the generalized periodic disturbance observer inside thevibrational torque controller 11 will be explained. In FIG. 17, anobserver gain Kob is added to the configuration of Embodiment 3. Ofcourse, even with the configurations of the other embodiments, similareffects can be obtained by using a configuration in which the observergain Kob is added to the inverse model Q_(n).

Since the observer gain Kob multiplies a gain to the inverse modelQ_(n), an error is actively imparted to the amplitude of the inversemodel transfer properties. Normally, the inverse of the control targetmodel P_(n) is set to be ON and the controller is operated in a statethat is matched as closely as possible to the true value in which thereis no model error. However, since a generalized periodic disturbanceobserver has a certain degree of robust stability with respect to modelerror, it is proposed that the feedback group gain be increased withinthe range of the robust stability. For example, an example of stabilityanalysis of a generalized periodic disturbance observer is shown in FIG.18.

FIG. 18 is a numerical example indicating the stability range when, withrespect to a control target model (true value) P_(n), the inverse modelQ_(n) thereof has amplitude error (vertical axis) and phase error(horizontal axis). In this numerical example, it can be seen that alarger amplitude error can be tolerated as the phase error approacheszero, and that instability occurs when the phase error exceeds ±90degrees.

Additionally, the portion of FIG. 18 indicated by the dotted linesindicates the area where the pole arrangement in the discrete systemapproaches the closest to the origin (where the quick response is thebest). In other words, this means that the quick response duringtransient changes is improved by setting the phase error as closely aspossible to 0 degrees mid applying an appropriate degree of observergain Kob.

In the present Embodiment 4, the robust stability range of thegeneralized periodic disturbance observer can be used to improve thetransient quick response of the vibration waveform tracking control byapplying an appropriate degree of observer gain Kob of the feedbackloop.

Embodiment 5

In the vibrational torque controller 11 in Embodiments 1-4, thegeneralized periodic disturbance observer system uses aperiodicdisturbance suppression controller contributing only a specificfrequency component. In the present Embodiment 5, the orders that are tobe suppressed are separately designated, and generalized periodicdisturbance observers for the respective orders are arranged inparallel. The parallel periodic disturbance compensation values aresummed in a compensation signal synthesis unit 19, thereby allowingperiodic disturbances in multiple frequency components to be suppressedsimultaneously.

Torque ripples are periodic disturbances that occur as a result ofelectromagnetic non-uniformities in the motor, mechanical imbalances,dead time in the inverter, and current sensor error, as well as othernonlinearities. As the order to be suppressed, for example, the firstorder, second order, sixth order, twelfth order or the like isdesignated in terms of the electrical frequency. The orders at whichtorque ripples tend to occur may be designated in accordance with thestructural properties and the number of poles in the motor.

As an example, a configuration in which two of the controlconfigurations in FIG. 13 are arranged in parallel will be explained. Asthe torque command value τ* and the torque detection value τ_(det) inthe parallel first control configuration and the torque command value τ*and the torque detection value τ_(det) in the parallel second controlconfiguration, the same values are inputted to the vibrational frequencycomponent extractor 12 and the ripple suppression frequency componentextractor 13.

Additionally, the sixth order is set as the suppression target order nof the parallel first control configuration and the twelfth order is setas the suppression target order n of the parallel second controlconfiguration. Therefore, the nth-order rotational phase nθ in theparallel first control configuration and the nth-order rotational phasenθ in the parallel second control configuration are different values.

Furthermore, the value obtained by summing the vibrational torquecommand value τ_(pd)* in the parallel first control configuration andthe vibrational torque command value τ_(pd)* in the parallel secondcontrol configuration is obtained as the output (vibrational torquecommand value τ_(pd)*) of the vibrational torque controller 11 in FIG.5.

Additionally, while vibrational control is used to simulate enginetorque pulses, in the four-cycle engines that are often used incommercially available automobiles, the fuel is exploded once for everytwo revolutions in each cylinder, so a large vibrational torque having afrequency that is the number of cylinders×0.5×rotation speed isgenerated. Additionally, in consideration of the high-frequencycomponents thereof, the engine vibration waveform may be simulated bydesignating the second order, the fourth order, the sixth order, theeighth order or the like of the mechanical frequency in a four-cylinderengine.

By arranging generalized periodic disturbance observers for thesemultiple control target orders in parallel, it is possible to simulatethe engine waveform while simultaneously achieving torque ripplesuppression.

Embodiment 6

Normally, the distorted waveforms in engine torque are high-frequencycomponents that are generated in synchronization with the enginerotation speed. Thus, as indicated in the above Embodiments 1-5, thevibrational torque controller 11 was formed by using a control systemsynchronized with the rotational phase detection value θ (=ƒω_(m) dt).

In a testing device such as a dynamometer, tests are normally performedby means of rotation-synchronized vibrations as mentioned above, but asa special case, it is also possible to implement vibrational controlthat is not synchronized with the motor rotation.

When doing so, aside from the frequency component of the ordersynchronized with the rotation used in torque ripple suppressioncontrol, a vibrational frequency component that is generated so as notto be synchronized with the rotation is superimposed. In this case, thenth-order rotational phase nθ is not inputted to the vibrationalfrequency component extractor 12 in FIG. 13, and a phase Θ′ (=ƒω′ dt)that is not synchronized with the nth-order rotational phase nθ isinputted.

In this case, ω′ is a value that is different from and not synchronizedwith the motor rotation speed ω_(m), which corresponds to the frequencycomponent used for vibrational control, ω′ is obtained bydifferentiating the phase Θ′. The phase Θ or ω′ is set separately andindependently of the motor rotation speed ω_(m).

Under such conditions in which the vibrational frequency component isnot synchronized, in the case of a configuration in which twoconfigurations having the control configuration in FIG. 13 are arrangedin parallel, as in Embodiment 5 (except that the value of n (hereinafterreferred to as n1) in the parallel first configuration is different fromthe value of n (hereinafter referred to as n2) in the parallel secondconfiguration; the phase Θ′ (hereinafter referred to as Θ1′) of thevibrational control in the parallel first configuration is differentfrom the phase Θ′ (hereinafter referred to as μ2′) of the vibrationalcontrol in the parallel second configuration), there is a possibility,depending on the motor rotation speed ω_(m), of cases occurring in whichthe frequency component (n1×ω_(m)) of the torque ripple suppressioncontrol in the parallel first configuration matches with the vibrationalfrequency component (ω2′=dΘ2′/dt) in the parallel second configuration.

In such cases, the same frequency component will be controlled in bothof the control systems that are arranged in parallel, and in some cases,there is a risk of causing control interference.

Therefore, in the present Embodiment 6, limited to cases in which anon-synchronized vibration test is to be implemented, thenon-synchronized vibrational frequency components (ω1′,ω2′) and thenth-order rotational frequency components, i.e., the torque ripplefrequency components (n1×ω_(m), n2×ω_(m)), in the respective parallelcontrol configurations are monitored, and when these frequencies match,the torque ripple suppression control is turned OFF in a controlconfiguration with a matching frequency.

As an example, in the case in which (n1×ω_(m)) in the parallel firstconfiguration matches with ω2′ in the parallel second configuration, thetorque ripple suppression control is turned OFF in the parallel firstconfiguration. In other words, in FIG. 13, U_(n)^({circumflex over ( )}) is set to zero.

According to the present Embodiment 6, it is possible to prevent controlinterference with a torque ripple suppression control system whenperforming non-synchronized vibrational control. Additionally, in theperiod during which the torque suppression control is turned OFF, thevibrational torque control system also serves the role of torque ripplesuppression, so the results of the engine waveform tracking control arenot affected,

Embodiment 7

In an actual engine, there are misfiring modes in which the fuelcombustion fails. For example, if just one cylinder in a four-cylinderengine misfires, then the engine enters a state in which torque is notoutputted once every four times.

In the present Embodiment 7, in order to support engine misfiring modes,a vibrational torque controller 11 is implemented with a generalizedperiodic disturbance observer in which a decimal order is designated.

For example, when implementing a single-cylinder misfiring mode in afour-cylinder engine, the 0.5-th order and multiples thereof aredesignated with respect to the mechanical rotation speed.

An example of the effects of the present Embodiment 7 is shown in FIG.19. The torque drops once every four times, so tracking is possible evenwhen such a vibrational torque command value is applied.

Although only specific examples of the present invention were explainedin detail above, it will be clear to a person skilled in the art thatvarious modifications and adjustments are possible within the scope ofthe technical concept of the present invention, and such modificationsand adjustments naturally belong within the scope of the claims.

1. A motor drive system for controlling shaft torque in a motor by usingan inverter, wherein the motor drive system comprises: a low-frequencytorque controller for outputting a low-frequency torque controlleroutput based on a torque command value and a torque detection value; avibrational torque controller for outputting a vibrational torquecommand value based on the torque command value, the torque detectionvalue and a rotational phase detection value; and a high-frequencyresonance suppression controller for outputting an inverter torquecommand value based on the torque detection value and a corrected torquecommand value obtained by adding the low-frequency torque controlleroutput to the vibrational torque command value.
 2. The motor drivesystem according to claim 1, wherein the high-frequency resonancesuppression controller has: a μ-synthesis controller for adding anoutput obtained by subjecting the corrected torque command value totransfer properties from a μ-synthesis controller command value input toa μ-synthesis controller output, to an output obtained by subjecting thetorque detection value to transfer properties from a μ-synthesiscontroller detection value input to a μ-synthesis controller output, andoutputting an inverter torque command value; and the low-frequencytorque controller implements PID control.
 3. The motor drive systemaccording to claim 1, wherein the vibrational torque controllercomprises: a vibration frequency component extractor for outputting annth-order frequency component vector of the vibrational torque commandvalue based on the torque command value and an nth-order rotationalphase obtained by multiplying, with the rotational phase detectionvalue, an order n of a torque ripple frequency component and a vibrationfrequency component to be controlled; a ripple suppression frequencycomponent extractor for outputting an nth-order frequency componentvector of periodic disturbances based on the torque detection value andthe nth-order rotational phase; a speed converter for outputting annth-order rotational frequency based on the nth -order rotational phase;a first inverse model multiplication unit for multiplying, with annth-order frequency component vector of the vibrational torque commandvalue, an inverse model to which a single frequency vector synchronizedwith the nth-order rotational frequency has been applied, and outputtingan nth-order frequency component vector of a vibration-induced periodicdisturbance command value; a second inverse model multiplication unitfor multiplying, with an nth-order frequency component vector of theperiodic disturbances, an inverse model to which a single frequencyvector synchronized with the nth-order rotational frequency has beenapplied, and outputting an nth-order frequency component vector of anoperation amount estimate value; a first subtractor for subtracting,from the nth-order frequency component vector of the operation amountestimate value, a value obtained by passing an nth-order frequencycomponent vector of the vibrational torque controller output through alow -pass filter, and outputting an nth-order frequency component vectorof the periodic disturbance estimate value; a second subtractor forsubtracting, from the nth-order frequency component vector of thevibration-induced periodic disturbance command value, the nth-orderfrequency component vector of the periodic disturbance estimate value,and outputting an nth -order frequency component vector of thevibrational torque controller output; and a compensation signalsynthesis unit for outputting the vibrational torque command value basedon the nth-order frequency component vector of the vibrational torquecontroller output and the nth-order rotational phase.
 4. The motor drivesystem according to claim 1, wherein the vibrational torque controllercomprises: a third subtraction unit for calculating a torque deviationbetween the torque command value and the torque detection value; afrequency component extractor for outputting an nth-order frequencycomponent vector of periodic disturbances based on the torque deviationand an nth-order rotational phase obtained by multiplying, with therotational phase detection value, an order n of a torque ripplefrequency component and a vibration frequency component to becontrolled; a speed converter for outputting an nth-order rotationalfrequency based on the nth -order rotational phase; an inverse modelmultiplication unit for multiplying, with the nth-order frequencycomponent vector of the periodic disturbances, an inverse model to whicha single frequency vector synchronized with the nth-order rotationalfrequency has been applied, and outputting an nth-order frequencycomponent vector of an operation amount estimate value; an adder foradding the nth-order frequency component vector of the operation amountestimate value to a value obtained by passing an nth-order frequencycomponent vector of the vibrational torque controller output through alow-pass filter, and outputting the nth-order frequency component vectorof the vibrational torque controller output; and a compensation signalsynthesis unit for outputting the vibrational torque command value basedon the nth-order frequency component vector of the vibrational torquecontroller output and the nth-order rotational phase.
 5. The motor drivesystem according to claim 1, wherein the vibrational torque controllercomprises: a third subtraction unit for calculating a torque deviationbetween the torque command value and the torque detection value; afrequency component extractor for outputting an nth-order frequencycomponent vector of periodic disturbances based on the torque deviationand an nth-order rotational phase obtained by multiplying, with therotational phase detection value, an order n of a torque ripplefrequency component and a vibration frequency component to becontrolled; a speed converter for outputting an nth-order rotationalfrequency based on the nth -order rotational phase; an inverse modelmultiplication unit for multiplying, with the nth-order frequencycomponent vector of the periodic disturbances, an inverse model to whicha single frequency vector synchronized with the nth-order rotationalfrequency has been applied, and determining an nth-order frequencycomponent vector of an operation amount estimate value; an integratorfor integrating the nth-order frequency component vector of theoperation amount estimate value, and outputting the nth-order frequencycomponent vector of the vibrational torque controller output; and acompensation signal synthesis unit for outputting the vibrational torquecommand value based on the nth-order frequency component vector of thevibrational torque controller output and the nth-order rotational phase.6. The motor drive system according to claim 1, wherein the vibrationaltorque controller comprises: a vibration frequency component extractorfor outputting an nth-order frequency component vector of thevibrational torque command value based on the torque command value andan nth-order rotational phase obtained by multiplying, with therotational phase detection value, an order n of a torque ripplefrequency component and a vibration frequency component to becontrolled; a ripple suppression frequency component extractor foroutputting an nth-order frequency component vector of periodicdisturbances based on the torque detection value and the nth-orderrotational phase; a speed converter for outputting an nth-orderrotational frequency based on the nth -order rotational phase; a firstinverse model multiplication unit for multiplying, with an nth-orderfrequency component vector of the vibrational torque command value, aninverse model to which a single frequency vector synchronized with thenth-order rotational frequency has been applied, and outputting annth-order frequency component vector of a vibration-induced periodicdisturbance command value; a second inverse model multiplication unitfor multiplying, with an nth-order frequency component vector of theperiodic disturbances, an inverse model to which a single frequencyvector synchronized with the nth-order rotational frequency has beenapplied, and outputting an nth-order frequency component vector of anoperation amount estimate value; a first multiplier for multiplying anobserver gain with the nth-order frequency component vector of thevibration-induced periodic disturbance command value and outputting aresult to a second multiplier; a second multiplier for multiplying anobserver gain with the nth-order frequency component vector of theoperation amount estimate value and outputting a result to a firstsubtractor; a first subtractor for subtracting, from the output of thesecond multiplier, a value obtained by passing an nth-order frequencycomponent vector of the vibrational torque controller output through alow-pass filter, and outputting an nth-order frequency component vectorof the periodic disturbance estimate value; a second subtractor forsubtracting, from the output of the first multiplier, the nth -orderfrequency component vector of the periodic disturbance estimate value,and outputting an nth-order frequency component vector of thevibrational torque controller output; and a compensation signalsynthesis unit for outputting the vibrational torque command value basedon the nth-order frequency component vector of the vibrational torquecontroller output and the nth-order rotational phase.
 7. The motor drivesystem according to claim 1, wherein the vibrational torque controllercomprises: a third subtraction unit for calculating a torque deviationbetween the torque command value and the torque detection value; afrequency component extractor for outputting an nth-order frequencycomponent vector of periodic disturbances based on the torque deviationand an nth-order rotational phase obtained by multiplying, with therotational phase detection value, an order n of a torque ripplefrequency component and a vibration frequency component to becontrolled; a speed converter for outputting an nth-order rotationalfrequency based on the nth -order rotational phase; an inverse modelmultiplication unit for multiplying, with the nth-order frequencycomponent vector of the periodic disturbances, an inverse model to whicha single frequency vector synchronized with the nth-order rotationalfrequency has been applied, and outputting an nth-order frequencycomponent vector of an operation amount estimate value; a multiplier formultiplying an observer gain with the nth-order frequency componentvector of the operation amount estimate value, and outputting a resultto an adder; an adder for adding the output of the multiplier to a valueobtained by passing the nth-order frequency component vector of thevibrational torque controller output through a low-pass filter, andoutputting the nth-order frequency component vector of the vibrationaltorque controller output; and a compensation signal synthesis unit foroutputting the vibrational torque command value based on the nth-orderfrequency component vector of the vibrational torque controller outputand the nth-order rotational phase.
 8. The motor drive system accordingto claim 1, wherein the vibrational torque controller comprises: a thirdsubtraction unit for calculating a torque deviation between the torquecommand value and the torque detection value; a frequency componentextractor for outputting an nth-order frequency component vector ofperiodic disturbances based on the torque deviation and an nth-orderrotational phase obtained by multiplying, with the rotational phasedetection value, an order n of a torque ripple frequency component and avibration frequency component to be controlled; a speed converter foroutputting an nth-order rotational frequency based on the nth -orderrotational phase; an inverse model multiplication unit for multiplying,with the nth-order frequency component vector of the periodicdisturbances, an inverse model to which a single frequency vectorsynchronized with the nth-order rotational frequency has been applied,and determining an nth-order frequency component vector of an operationamount estimate value; a multiplier for multiplying an observer gainwith the nth-order frequency component vector of the operation amountestimate value and outputting a result to an integrator; an integratorfor integrating the output of the multiplier, and outputting annth-order frequency component vector of the vibrational torquecontroller output; and a compensation signal synthesis unit foroutputting the vibrational torque command value based on the nth-orderfrequency component vector of the vibrational torque controller outputand the nth-order rotational phase.
 9. The motor drive system accordingto claim 3, having multiple vibrational torque controllers of differentorders n; wherein a value obtained by summing the outputs of each of thevibrational torque controllers is used as the vibrational torque commandvalue.
 10. The motor drive system according to claim 9 wherein, when thenth-order rotational phase is not inputted to the vibration frequencycomponent extractor and a phase that is not synchronized with thenth-order rotational phase is inputted, unsynchronized vibrationfrequency components and nth-order rotational frequencies inparallel-stage control structures are separately monitored, and whenthese frequencies match, the nth-order frequency component vectors ofthe operation amount estimate values in the control structures inmatching stages are set to zero.
 11. The motor drive system according toclaim 3, wherein the order n of the vibrational torque controllerincludes decimal numbers.
 12. A motor drive system according to claim 1,comprising: a drive motor for simulating engine explosion torque,connected to an input side of a test piece; an absorption motor forsimulating a load from wheels and a road surface, connected to an outputside of the test piece; a vibrational controller for outputting a firstinverter torque command value based on a torque detection value and arotational phase detection value of the drive motor; a speed controllerfor outputting a second inverter torque command value based on the motorrotation speed of the absorption motor; a drive motor inverter fordriving the drive motor based on the first inverter torque commandvalue; and an absorption motor inverter for driving the absorption motorbased on the second inverter torque command value.